| Magnesium-lithium alloy is the lightest alloy among magnesium alloys.It has high specific strength and specific rigidity.It is the most ideal alloy material for the pursuit of lightweight component structure.Therefore,this alloy is widely used in aerospace fields such as satellites.On the components,it can improve its effective load capacity and reduce the load.In this paper,the as-cast Mg-9.45Li-0.69Zn-0.024Al alloy is used as the research object,and the Gleeble thermal simulation test machine is used to conduct the hot compression test:The Mg-9.45Li-0.69Zn-0.024Al alloy was studied the rheological behavior and established the constitutive equation.According to the DMM model,the hot working diagram of Mg-9.45Li-0.69Zn-0.024Al alloy was constructed.The hot working process parameter range of Mg-9.45Li-0.69Zn-0.024Al alloy was obtained.And the effect of thermal deformation conditions on Mg-9.45Li-0.69Zn-0.024Al alloy microstructure,macro texture and comprehensive mechanical properties was analyzed.The main conclusions are as follows:(1)Homogenizing the as-cast Mg-9.45Li-0.69Zn-0.024Al alloy.When the homogenization system is 360?×6 h,the homogenization effect of the alloy is better.At this time,the spheroidized a-Mg There are more phases,dispersed distribution,and less precipitated phases.In addition,the plasticity of the alloy is improved under this condition.(2)The rheological curve of Mg-9.45Li-0.69Zn-0.024Al alloy during hot compression is a typical dynamic recrystallization true stress-true strain curve.In the process of hot compression deformation of the alloy,there is an obvious dynamic softening phenomenon,and dynamic recrystallization is the main softening mechanism.As the deformation temperature increases,the peak stress ? peak decreases;as the strain rate increases,the peak stress ? peak increases.(3)The most commonly used Arrhenius-type constitutive model is used for modeling,and its hyperbolic sine form in the process of thermal compression deformation Arrhenius-type constitutive equation and the Z parameter expression of flow stress ?:?=5.733×107[sinh(0.037?)]2.66053exp[-95048/(RT)]?=(1/0.037)ln{(z/5.733×107)1/2.66053+[(z/5.733×107)2/2.66053+1]1/2}Z=?exp[95048/(RT)]The correlation coefficient(R)between the calculated value and the measured value of the peak stress under all experimental conditions is 0.9865,indicating that the Arrhenius-type constitutive model is suitable for the establishment of the constitutive equation of the alloy,Can more accurately predict the peak stress of Mg-9.45Li-0.69Zn-0.024Al alloy during hot compression deformationThe average deformation activation energy Q of Mg-9.45Li-0.69Zn-0.024Al alloy is 95.048 kJ/mol,and the stress index n is 2.66053(4)Based on the DMM model,the hot working drawing of Mg-9.45Li-0.69Zn-0.024Al alloy was constructed,and its analysis showed that the deformation temperature of the alloy is 290??325?,and the strain rate is 0.001s-1?0.3s-1 Area belongs to the alloy processing safety zone,and the energy dissipation efficiency ? value is as high as 40%.The region where the deformation temperature is 175??225?,the strain rate is 0.001s-1?1s-1,the deformation temperature is 290??325?,and the strain rate is 0.2s-1?1s-1 belongs to alloy rheological instability.Zone,the energy dissipation efficiency ? value is lower than 40%(5)At the same deformation temperature,with the increase of the strain rate,the grain size of the Mg-9.45Li-0.69Zn-0.024Al alloy decreases significantly;at the same strain rate,the grain size of the Mg-9.45Li-0.69Zn-0.024Al alloy decreases significantly;With the increase of temperature,the grain size of Mg-9.45Li-0.69Zn-0.024Al alloy shows a trend of decreasing first and then increasing(6)At the same deformation temperature,with the increase of the strain rate,the diffraction peak intensity of the(200)crystal plane of the ? phase in the XRD pattern of the Mg-9.45Li-0.69Zn-0.024Al alloy is significantly weakened,(211)The diffraction peak intensity of the crystal plane is significantly enhanced;at the same strain rate,with the increase of the deformation temperature,the diffraction pattern of the ? phase(110)crystal plane in the XRD pattern of the Mg-9.45Li-0.69Zn-0.024Al alloy The peak intensity is significantly enhanced(7)At the same deformation temperature,with the increase of strain rate,the a-Mg phase{0002} texture of Mg-9.45Li-0.69Zn-0.024Al alloy and the {200} texture of ?-Li phase The maximum pole density of Mg-9.45Li-0.69Zn-0.024Al alloy exhibits a trend of decreasing first and then increasing;at the same strain rate,with the increase of deformation temperature,the a-Mg phase {0002} texture and texture of Mg-9.45Li-0.69Zn-0.024Al alloy The maximum pole density of the {200} texture of the ?-Li phase showed a tendency to increase first and then decrease(8)Under the same deformation temperature,with the increase of the strain rate,the hardness of Mg-9.45Li-0.69Zn-0.024Al alloy shows an increasing trend;at the same strain rate,with the increase of the deformation temperature Increase,the hardness of Mg-9.45Li-0.69Zn-0.024Al alloy presents a trend of increasing first and then decreasing. |
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